1. Field of the Invention
The present invention relates to a hardness tester to measure hardness of a sample by forming an indentation on the surface of the sample.
2. Description of Related Art
In earlier development, for example, a hardness tester is known, in which a load is applied to the surface of a sample by an indenter so as to form an indentation thereon, and hardness of the sample is measured based on measured size and depth of the formed indentation (for example, see JP 10-132722A).
An indenter used for hardness test has various shapes such as conical, pyramid, and spherical, and they are exchanged according to a type of test, property of a sample and the like. Since a calculation formula to calculate hardness from measured data varies according to the indenter, it is necessary to change the calculation formula when the indenter is changed.
Further, even between indenters of same shape, obtained hardness values include error caused by number of use of the indenter. Therefore, it is necessary to use same indenter to reduce the error among a plurality of measurements. Thus, it is necessary to identify each of the indenters.
In earlier development, indenters of same or different shape are distinguished from each other by means of only visual observation.
However, when shape of an indenter is identified by means of visual observation, a user may misidentify the shape of the indenter in exchanging the indenter or may not find out that a set program or calculation formula is different from that for the currently assembled indenter. Thus, it has been problematic that incorrect hardness value is obtained as a result.
Further, it is difficult to distinguish indenters of same shape as each other, it has been problematic to select an identical indenter.